Carbon nanotube composite microspheres as a highly efficient solid-phase microextraction coating for sensitive determination of phthalate acid esters in water samples

Multiwalled carbon nanotubes (MWCNTs) on polystyrene (PS) microspheres have been designed and prepared by layer-by-layer assembly via electrostatic interaction. MWCNTs@PS was characterized by scanning electron microscopy (SEM) and thermogravimetric analysis (TGA). The new materials were employed as a novel solid-phase microextraction (SPME) coating to enrich trace level of phthalate acid esters (PAEs) in water samples. Five PAEs, di-n-butyl phthalate (DBP), benzyl butyl phthalate (BBP), di-2-ethylhexyl adipate (DEHA), di-2-ethylhexyl phthalate (DEHP) and di-n-octyl phthalate (DOP), were studied in this work. The Box-Behnken design was applied to calculate optimum extraction factors affecting the extraction efficiency using a response surface. In the optimized conditions, the developed technique achieved high enrichment factors (738-2347), low limits of detection (0.0012-0.018 μg L−1) and wide linearity (0.001-5 μg L−1) for detecting PAEs. The method was successfully applied to analyze PAEs in real environmental water samples with recovery ranging from 73.4% to 103.8%. The results demonstrated that MWCNTs@PS are a promising coating material in the SPME of PAEs at trace levels from environmental samples.